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1.
The CdS/TiO 2NTs composite was prepared by a simple two-step chemical solution routes to directly transfer trititanate nanotubes to TiO 2NTs and simultaneously coupled with CdS nanoparticles. The results of XRD, TEM, Diffuse reflectance UV-Visible absorption spectra revealed that the CdS nanoparticles were homogeneously embedded on the surface of TiO 2NTs and the absorption spectrum of TiO 2NTs was extended to visible region. The activity of hydrogen production by photocatalytic water decomposition for the CdS/TiO 2NTs composite was examined under visible light irradiation ( λ > 400 nm) and the quantity of H 2 evolution was ca. 1708 μL/g for 6 h. 相似文献
2.
Mesoporous TiO 2 thin films were prepared by hydrothermal-oxidation of titanium metal thin films, which were obtained by DC magnetron sputtering technique. Gold nanoparticles, which were prepared by reduction of HAuCl 4, were embedded into the holes of the mesoporous TiO 2 films by capillary method followed by annealing in air up to 400 °C. The size of pore of TiO 2 films is about 100 nm and that of Au nanoparticles is about 10 nm in average. The morphology of the films was analyzed by field emission scanning electron microscope (FE-SEM) and scanning probe microscopes (SPMs). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of methylene blue solution are discussed. The obtained results show that the dispersion of Au nanoparticles on the mesoporous TiO2 matrix will help enhancing the photocatalytic activity with respect to pure TiO 2 under visible light irradiation. 相似文献
3.
In order to utilize the photocatalytic function of TiO 2 nanoparticles in materials manufactured from organic polymeric compounds, such as paper, resins, and textiles, TiO 2 nanoparticles supported on aluminosilicate, which contained 1, 5, and 10 wt% of TiO 2 were prepared by mixing commercial TiO 2 nanoparticles and porous aluminosilicate at pH 7 in a cationic surfactant aqueous solution. Most of the supported TiO 2 nanoparticles on the aluminosilicate surface were observed by TEM–EDS (energy depressive X-ray spectroscopy) analysis. TiO 2 nanoparticles supported on aluminosilicate reduced the formaldehyde concentration from 20 to 0 ppm after UV irradiation for 20 h; the reduction of formaldehyde concentration under UV irradiation was obviously different from that in the dark. Moreover, a paper mixed with 20 wt% of TiO 2 nanoparticles supported on aluminosilicate bleached the stains colored with cigarette tar after UV irradiation for 6 h. However, the paper maintained its initial tensile strength even after UV irradiation for 1 year; in contrast, the paper mixed with a simple dry mixture of TiO 2 powder and aluminosilicate lost approximately half of its initial tensile strength after a year. TiO 2 nanoparticles supported on aluminosilicate could exhibit photocatalytic activity without decomposing the organic polymeric compounds. 相似文献
4.
Two types of disperser namely, a high speed agitation bead mill and a colloidal mill, were used for the dispersion behavior control of TiO 2 nanoparticles (20 nm in average primary diameter) in an aqueous suspension. A composite thin film raging in thickness from 90 to 400 nm was prepared from the coating suspension following the addition of a commercial ethyl silicate oligomer binder into the prepared suspension by means of a spray coating method. The mean aggregate size of TiO 2 nanoparticles in the aqueous suspension was found to be 80 nm and 290 nm in diameter, respectively, when using the agitated bead and colloidal milling methods. Large aggregates on the order of several hundred nanometers were found to remain in the suspension after colloidal milling. Further, a fine dispersion of TiO 2 nanoparticles in the thin film produced using the agitation bead milling process promoted the photocatalytic activity and enhanced transparency of the film for visible light. The aggregate structure of TiO 2 nanoparticles in an aqueous suspension was well maintained in the film prepared by a spray coating process. 相似文献
5.
Highly efficient visible light TiO 2 photocatalyst was prepared by the sol-gel method at lower temperature (≤300 °C), and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The effects of the heat treatment temperature and time of the as-prepared TiO 2 on its visible light photocatalytic activity were investigated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength ≥ 400 nm). Results show that the as-prepared TiO 2 nanoparticles possess an anatase phase and mesoporous structure with carbon self-doping and visible photosensitive organic groups. The visible light photocatalytic activity of the as-prepared TiO 2 is greatly higher than those of the commercial TiO 2 (P-25) and other visible photocatalysts reported in literature (such as PPy/TiO 2, P3HT/TiO 2, PANI/TiO 2, N-TiO 2 and Fe 3+-TiO 2) and its photocatalytic stability is excellent. The reasons for improving the visible light photocatalytic activity of the as-prepared TiO 2 can be explained by carbon self-doping and a large amount of visible photosensitive groups existing in the as-prepared TiO 2. The apparent optical thickness ( τapp), local volumetric rate of photo absorption (LVRPA) and kinetic constant ( kT) of the photodegradation system were calculated. 相似文献
6.
The use of TiO 2 as photocatalyst to degrade the organic compounds is an effective method of oxidation process and has been widely studied in environmental engineering. However, TiO 2 absorbed the UV light which is only small part of sunlight reaching earth surface to activate photocatalytic procedure effectively is a major disadvantage. Therefore, studies on the development of new TiO 2 wherein its photocatalytic activity can be activated by visible light which is the major part of sunlight will be valuable for field application. In this study, we evaluate the photocatalytic degrading efficiency of porphyrins/TiO 2 complexes on the organic pollutants under irradiation with visible light ( λ = 419 nm). The results showed that the photodecomposition efficiency of 2,4-dichlorophenol (2,4-DCP) wastewater by using porphyrin/TiO 2 irradiated under visible light for 4 h was up to 42-81% at pH 10. These evidences reveal that the system of porphyrin/TiO 2 complexes has also significantly efficiency of photocatalytic degradation for some hazardous or recalcitrant pollutants under visible light irradiation. 相似文献
7.
N and B co-doped TiO 2 nanoparticles were prepared by a facile one-step combustion reaction where Ti(OC 4H 9) 4 and H 3BO 3 were used as the precursors and urea served as the fuel and the N source. The formation of TiO 2 nanoparticles and the co-doping of N and B into the TiO 2 matrix lattices were achieved simultaneously. Our experimental results have shown that the optical absorption edges of the N and B co-doped TiO 2 nanoparticles significantly shift toward long wavelength compared to that of non-doped TiO 2 photocatalysts. The estimated optical bandgap of the N&B co-doped TiO 2 nanoparticles is 2.13 eV, which is much smaller than that of pure anatase TiO 2 (3.18 eV). We further studied the photocatalytic activity of the synthesized N&B co-doped TiO 2 nanoparticles through the decomposition of acetic acid, showing that the N&B co-doped TiO 2 exhibits superb photocatalytic activity and visible light response compared to one of the best commercially available TiO 2 photocatalysts, P25. 相似文献
8.
Polyaniline (PANI)/TiO 2 composites with different ratios of TiO 2 to PANI were prepared using a hydrothermal–chemisorption process, and their photocatalytic activities for the decomposition of four organic vapors (benzene, toluene, ethyl benzene, and xylene (BTEX)) under both visible- and UV-light irradiation were investigated. Thermal-gravimetric analysis indicated that PANI and TiO 2 could be successfully combined to form PANI/TiO 2 composites. Both X-ray diffraction and Fourier transform infrared results confirmed that the PANI/TiO 2 composites included anatase phase, but not rutile phase TiO 2. The UV–visible spectra demonstrated that the light absorption region extended well into the visible-light range for all prepared PANI/TiO 2 composites. Under visible-light irradiation, the average photocatalytic decomposition efficiencies of PANI/TiO 2 composite increased over a 3-h period from 16 to 61, 28–92, 40–95, and 53–96% for BTEX, respectively, as their ratios of TiO 2 to PANI increased from 5 to 200. The average photocatalytic decomposition efficiencies of PANI/TiO 2 composite over a 3-h period under visible-light irradiation decreased from 58 to 16, 92–45, 94–62, and 94–69% for BTEX, respectively, as the air flow rate increased from 1 to 4 L min −1. Moreover, the PANI/TiO 2 composites showed higher decomposition efficiency than as-prepared TiO 2 and P25 TiO 2 powders under both UV- and visible-light irradiation, demonstrating improved photocatalytic performance of the PANI/TiO 2 composites. 相似文献
9.
An efficient visible light photocatalyst has been prepared from TiO 2 nanoparticles and a partly conjugated polymer derived from polyvinyl chloride (PVC). It was characterized by transmission
electron microscopy (TEM), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), Fourier-transform
infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic
activity of the as-prepared photocatalyst was evaluated by the photocatalytic degradation of Rhodamine B (RhB) under visible
light irradiation. The XPS, FT-IR, and Raman spectra show that the partly conjugated polymer derived from PVC exists on the
surface of the TiO 2 nanoparticles. The UV–Vis DRS, XRD, and TEM results reveal that the modification of the partly conjugated polymer can obviously
improve the absorbance of the TiO 2 nanoparticles in the range of visible light and hardly affect their size and crystallinity. The visible light photocatalytic
activity of the as-prepared TiO 2 nanocomposites is higher than that of commercial TiO 2 (Degussa P25) and comparable with those of visible light photocatalysts reported in the literature. Their visible light photocatalytic
stability is also good. The reasons for their excellent visible light photocatalytic activity and the major factors affecting
their photocatalytic activity are discussed. 相似文献
10.
Using a low-temperature, simple, and economic processing technique, TiO 2 nanoparticles (rutile phase) are immobilized in an inorganic matrix and then deposited on glass for bacteria inactivation in water. Using this low thermal budget method (maximum processing temperature of 220 °C), thin films of immobilized TiO 2 nanoparticles are obtained so that practical water decontamination after UV radiation is possible by avoiding the additional step of catalyst separation from treated water. In order to validate the photocatalytic activities of these TiO 2 nanoparticles (prepared as thin films), they were tested for bacteria inactivation in water under UV–A radiation ( λ > 365 nm), while extensive characterizations by dynamic light scattering, X-ray diffraction, ultra violet–visible absorption spectroscopy, fourier-transform infra red spectroscopy, and profilometry were also carried out. Despite previous reports on the low or lack of photocatalytic activity of rutile-phase TiO 2, inactivation of Escherichia coli in water was observed when thin films of this material were used when compared with the application of UV radiation alone. Physical characterization of the films suggests that size and concentration-related effects may allow the existence of photocatalytic activity for rutile-TiO 2 as long as they are exposed under UV–A radiation, whereas no effect on bacteria inactivation was observed for thin films in the absence of TiO 2 or radiation. In brief, a low thermal budget process applied to thin films based on TiO 2 nanoparticles has shown to be useful for bacteria inactivation, while possible application of these films on widely available substrates like polyethylene terephthalate materials is expected. 相似文献
11.
Nanocrystalline particles of pure anatase titania were prepared by two different methods. One is the sol-gel method at ambient temperature using ultrasonication (TiO 2-SG-US) and conventional stirring method (TiO 2-SG-S) and the other by surfactant assisted hydrothermal synthesis (TiO 2-HT). More uniform distribution/dispersion of the nanoparticles (SEM), marginally higher surface area, better thermal stability and phase purity are some of the advantages of preparation of nanocrystalline titania by sol gel ultrasonication method and hydrothermal synthesis method. The behavior of anatase titania in photocatalytic decomposition of methylene blue in aqueous medium was studied as a function of the method of preparation and the crystallite size. The nanoparticles prepared by ultrasonication method were more effective than both, the sample prepared by conventional stirring method and commercial Degussa P-25. The higher photocatalytic activity of TiO 2-SG-US is attributed to the more uniform size of the particles as compared to TiO 2-SG-S samples. Both TEM and XRD data on TiO 2-HT samples reveal a uniform and nanocrystalline TiO 2 particles, which showed photocatalytic activity in both UV and visible region although brookite phase was also present. 相似文献
12.
Herein, titanium dioxide (TiO2)-coated vertically aligned silicon nanowires (SiNWs/TiO2) were fabricated and evaluated for photocatalytic degradation of organic dyes. Aligned SiNWs arrays were prepared by facile metal-assisted chemical-etching process with varying the etching time that was followed by TiO2 nanoparticles coating using sputtering technique. The TiO2 film crystallized in pure anatase phase with an average crystalline size of 50 nm, as was elucidated with X-ray diffraction studies. SEM analysis showed nanowires with varying lengths from 2.5 to 13.5 µm and confirmed the homogenous surface decoration with TiO2. The homogeneous distribution of TiO2 nanoparticles on nanowires was co-evidenced with Energy-Dispersive X-ray spectroscopy (EDX) and Raman spectra analysis. The developed SiNWs/TiO2 was exploited for photocatalytic degradation of methylene blue; the role of hydrogen peroxide was also elucidated. The highest photocatalytic efficiency of 96% was achieved for SiNWs/TiO2 with optimum nanowire length of 3.5 μm. The developed photocatalyst was found to be almost stable even after 190 days (~?5 months) and could be used as reusable and easily removable photocatalysts. The current study highlighted the SiNWs/TiO2/H2O2 system as excellent candidate for water remediation applications. 相似文献
13.
In this study, polyacrylamide gel method was used for preparation of pure and mixed phase TiO 2 nanoparticles. The influence of synthesis conditions on the physicochemical properties of products was investigated. It was found that the type of acid, which was used for acidifying the precursor solution together with calcination temperature can affect the phase structure, crystalline size, morphology and thereby photocatalytic activity of obtained TiO 2 nanoparticles. Different trends were observed during the phase transformation, particle growth, shift in energy of band gap with the change in tensile strain to compressive strain of the prepared TiO 2 nanomaterial. X-ray diffraction (XRD) showed that prepared nanocrystals, which were calcined at 450 °C have pure anatase and anatase–rutile mixed structures. The prepared samples having crystallite size between 5 nm and 60 nm were observed at different calcination temperatures. In addition, the photocatalytic activities of the prepared samples were evaluated by monitoring the degradation of Cresol Red (CR). The results show that the photocatalyst (TEC I), exhibits the highest photocatalytic efficiency where 94.7% of CR can be decomposed after UV exposure for 75 min. 相似文献
14.
(Zn, N)-codoped TiO 2 nanoparticles were prepared by the sol–gel method. X-ray diffraction (XRD) results testified that anatase samples were obtained. Transmission electron microscopy (TEM) patterns revealed that the average grain size of all the samples is about 15 nm and the Zn doping caused obvious particle aggregation. The Brunauer–Emmett–Teller (BET) surface areas of the samples were measured to testify the aggregation. The Zn doping caused slight blue-shift of absorption edge by the ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) measurements. The photocatalytic activity for the degradation of methylene blue (MB) solution was best enhanced in the (Zn, N)-codoped TiO 2 with 1 at.% Zn doping level. Photoluminescence (PL) emission spectra of the samples were also investigated, which revealed that the oxygen vacancy and isolated N 2p states played important roles in the photo-generated charge carrier recombination in the (Zn, N)-codoped TiO 2. It was suggested that the doping induced oxygen vacancies could promote the photocatalytic oxidation processes. 相似文献
15.
DDAT(S-1-Dodecyl-S′-(α, α′-dimethyl-α″-acetic acid) trithiocarbonate) modified TiO 2 photocatalysts were prepared by hydrothermal treatment before TiO 2 crystallization. The adsorption of DDAT onto the surface of titania nanoparticles led the shifting of the onset wavelength of the optical absorption in the visible range corresponding to ligand-to-metal charge transfer transition within the surface-modified complex. The interaction of TiO 2 nanoparticles with DDAT was investigated by infrared spectra. The XRD indicated that the modification process could not influence the crystallite phase of TiO 2. The photocatalytic studies suggested that the DDAT modified TiO 2 photocatalysts showed enhanced photocatalytic efficiency of photodegradation of 2,4-dichlorophenol compared with the as-prepared TiO 2 under visible-light irradiation. 相似文献
16.
Holmium-doped TiO 2 nanoparticles with high photocatalytic activities were prepared by sol–gel method and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, and surface area measurement by nitrogen adsorption in this study. Experimental results indicated holmium doping could increase the surface area of TiO 2 nanoparticles, and inhibit the growth of crystalline size and the anatase-to-rutile phase transformation. The results of photodegrading methyl orange showed holmium doping improved the photocatalytic activity of TiO 2, and the reasons could be attributed to the synergetic effects of large surface areas, small crystallite size, lattice distortion and more charge imbalance of holmium-doped TiO 2. In our experiment, the optimal doped amount was 0.3 mol.% for the maximum photocatalytic degradation ratio when holmium-doped TiO 2 was calcined at 500 °C, and the optimal calcined temperature was 600 °C when the doped amount was 0.5 mol.%. 相似文献
17.
Zirconia and nitrogen-doped TiO 2 powder was synthesized using a polymer complex solution method for the preparation of an enhanced visible light photocatalyst. The produced catalysts were characterized via the Brunauer, Emmett, and Teller method (BET), X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, and UV–Vis spectrophotometry analyses. The N-doped TiO 2/ZrO 2 photocatalyst showed a high specific surface area and small crystal sizes. The XPS spectra of the N-doped TiO 2/ZrO 2 sample indicated that nitrogen was doped into the TiO 2 lattice and enhanced the photocatalytic activity. The UV–Vis absorption spectra of the N-doped TiO 2/ZrO 2 sample noticeably shifted to the visible light region compared to that of the TiO 2. The photocatalytic activities of the prepared catalysts were evaluated for the decomposition of gaseous NO x under UV and visible light irradiations. The photocatalytic activities of N-doped TiO 2/ZrO 2 were much greater than those of commercial Degussa P25 in both the UV and visible light regions. The high photocatalytic activity can be attributed to stronger absorption in the visible light region, a greater specific surface area, smaller crystal sizes, more surface OH groups, and to the effect of N-doping, which resulted in a lower band gap energy. 相似文献
18.
ZrO 2/TiO 2 nanoparticles with various Zr/Ti ratios (0–0.9) were prepared by a polymer complex solution method (PCSM). The prepared samples were characterized using transmission electron microscopy (TEM), the Brunauer, Emmett & Teller (BET) method, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The ZrO 2/TiO 2 photocatalyst showed a high specific area and small crystal size. The XRD pattern for the Zr/Ti = 0.1 sample indicated that the addition of ZrO 2 stabilized the anatase phase of TiO 2 up to 800 °C. The photocatalytic activity of Zr/Ti = 0.1 sample was higher than that of the TiO 2 sample and commercially available Degussa P25. The high photocatalytic activity can be attributed to stronger adsorption in the visible light region, higher specific area, smaller crystal size and increased surface OH groups. 相似文献
19.
The N-doped TiO 2 nanotube array films were fabricated directly by one-step electrochemical anodic oxidation of Ti foils in an HF electrolyte
containing ammonium and nitrate ions. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron
microscopy (SEM), energy dispersive spectrometer (EDX), and ultraviolet–visible (UV–vis) absorption spectroscopy, respectively.
The photocatalytic activities were evaluated by the degradation of methyl orange (MO) under visible light irradiation. The
results showed that N dopant was successfully introduced into the TiO 2 nanotube array films. The N-doped TiO 2 nanotube array films showed a red shift and an enhancement of the absorption in the visible light region compared to the
undoped sample. The photocatalytic activities of the N-doped TiO 2 samples were much higher than those of the undoped sample. A maximum enhancement of photocatalytic activity was achieved
for the N-doped TiO 2 sample prepared in 0.07 M HF electrolyte containing 1.0 M NH 4NO 3, and 81% of MO was degraded in 150 min under visible light irradiation. 相似文献
20.
TiO 2 nanoparticles doped with different content of Ce ion were prepared by sol–gel method. The samples were characterized by XRD, XPS, TEM, UV–Vis, and PL, the photocatalytic activity was evaluated by photocatalytic degradation of methylene blue (MB) under the irradiation of fluorescent lamp. The results indicate that Ce ion is incorporated into the lattice of TiO 2, which can restrain the increase of grain size, broaden the absorption region to visible light, and inhibit the recombination of the photo-generated electron and hole pairs. Moreover, the photocatalytic activity of Ce-TiO 2 in MB degradation is evidently enhanced. The MB degradation rate of the sample with Ce:Ti = 0.33% (molar ratio) in 8 h is 90.03%, which is much higher than that of P25 (68.19%). 相似文献
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